1. Field of the Invention
This invention relates to an apparatus for generating electrical power from flowing water. More particularly, this invention relates to an apparatus for the generation of electrical power from low head installations.
2. Statement of the Prior Art
Throughout the United States there are many existing dams and other water flow control structures which are low head and can be used for power generation without excessive civil engineering construction. A problem in using such structures for power generation is that these structures are typically provided with spillways which must be capable of handling flood water conditions. While the spillways would be a desirable location to place a turbine, this is not possible since the spillway must not be permanently blocked.
One solution for using low head installations is to provide a powerhouse which is in a spillway when the turbine is to generate electricity. During flood conditions, the powerhouse structure is lifted within the spillway to provide generally uninterrupted flow of water to relieve the flood conditions. Such an apparatus is described in my commonly assigned U.S. Pat. No. 4,319,142. In the aforementioned patent, the powerhouse structure is lifted vertically within the spillway. One difficulty encountered from the powerhouse structure taught in the aforementioned patent is that a great deal of energy is required to lift the powerhouse. U.S. Pat. No. 4,143,990, to Atencio teaches a powerhouse structure upstream of a dam and lifted or pivoted to a position with the powerhouse upstream of the spillway. Again, such structure would require a great deal of energy and the air chambers used to assist in generating bouyancy are difficult to fabricate to insure airtightness. Additionally in the latter teaching, flow control through the spillway is all or nothing. That is, either all the water is directed through the turbine when the powerhouse is in a power generating position, or all of the water is permitted to flow uninterrupted through the spillway when the turbine powerhouse is in a bypass position.